Coupling device



NOV; 4, 1959 J. J. AYRES ET COUPLING DEVICE l a I l 2 Sheets-Sheet 1 Filed April 19, 1957 IE I I I I l l I I I I I I I I I l I I I l man/r41: JAY J. AYERS FRED [Sm-12m r v I g 7 III i; 3 5 w I. 3 w n u u "n \N 4 "u .0 H \I T II 3:: f N R /4\ ll. \N\\\\\\\\\\\\\\\\\\\\\\ I \N K E" N I $5 I NL BY EERALD BRAUER:

II'TOIA/IY Nov. 24, 1959 J, J. AYREs ET AL COUPLING DEVICE 2 Sheets-Sheet 2 Filed April 19, 1957 M'MWIWII J. AYR'ES mam BALD

E2 BRAUER COUPLING DEVICE Jay: J, Ayres,.Sicklerville, Fred Cohen, Collingswo'od, and Gerald Brauer, Marg'ate, N.J., assignors to Radio Corporation of America, a corporation of Delaware I g annals Apr-i119, 1957, Serial No. 653,828

7 Claims; oi. ass-s3 Anotjer object of the invention is to provide an impgovedicoup ling device in, the form of an. adjustable GQQX t ansmission. line. and. tap for use with a trans- Another object of thejinvention is to provide an improyed'coupl'ing' device'that is in the form of a coaxial transmission line-and tap, that is primarily designed to be; used, with a coaxial resonant cavity, and that can be adjusted to provide the desired loading to the resonant ver a widerange of operating frequencies.

5 Theinvention is primarily designed to be used with a eoagiialresonantcavity having a hollow, cylindrical, outer conductor and a cylindrical inner conductor concentrh cally positionedjwithin theouter conductor. Briefly, the invention provides means for adjustingv the: loading pre-v sent dby, ancoaxial transmission line which iscoupledto the, c" axial resonant cavity. In accordance with the inven, igtheg inner conductorof a section of coaxial tiarlsmission. line. is arranged .so. that it. can be moved along its longitudinal axiswithrespect to the hollow outer con uctorfof.thetransmission line. The outer conductor ofj the coaxial transmission line section and the outer no not, the. coaxial resonantcavity are. positioned;

thatfltheyi contact each other longitudinally along a j ntwall portionfor at least-aportion of their respective lengths. Bothouter. conductors have a longitudinal slot in they joint;wa ll .portion to provide an opening between the. resonant, cavityand the transmission line section. A

conductive.connecting'element. ortap is. fastened to the movable, inner conductor of the transmission line, section.

and extendsradially from the movable inner. conductor through theslot: without, touching the jointwall portion andiwithouttouching. either of-the outer conductors. The clonne ting element extends into the resonant cavity so thatit. contactsthe, inner conductor of the cavity over at least; a portion. of the. movement of the inner conductor on;the,transmission-linesection. The point at which the connectingelementcontacts the inner conductor of the resonant cavity determines the loading presented to the rpsonant cayity by the transmission line section. In a preferred embodiment of the; invention, an additional,

elementistalsoprovided to permit the'resonant cavity to be frequency. tuned, In addition to being used Witha coaxial :res onant cavity, the coupling device canalso be nsled awith coaxialtransmission lines and" with hollow waye-guidesand cavities.

flihejnyentioiris explained in detail in connection with thelaccompany ing drawing, in which: v

1showsalongitudinal view, partly in section, of a resonant cavity and a coupling device in accordance withthe inyention; and

United States Patent O Figs. 2 and 3 show transverse cross-sectional views taken along the lines 2-2 and 3--3, respectively, of the view shown in Fig. 1.

In the three figures, like reference numerals refer to like parts. The coupling device comprises a coaxial transmission line 10 having a hollow, metallic, cylindrical outer conductor 12, and a hollow metallic, concentric, cylindrical inner conductor 14. The outer conductor 12 of the transmission line 10 is arranged so that it is held in a stationary position. This transmission line 10 is intended to couple power from a coaxial resonant cavity 16 and apply this power to some load, not shown, such asan antenna. The inner conductor 14 of the transmission line 10 comprises a fixed portion 18 which extends within the outer conductor 10 towards the load, and a movable portion 20, one end of which is designed to telescope inside, as shown, or outside the fixed portion 18 of the inner conductor 14. At the other end of the movable portion 20 of the inner conductor 14, a metallic, connecting element or. tap 22 is attached and electrically connected to the movable portion 20. This connecting element 22 extends radially from the movable portion 20 of the inner conductor 14 towards and into the resonantcavity 16.

The resonant cavity 16 comprises a hollow, metallic, cylindrical outer conductor 24-, and a hollow, metallic, concentric, cylindrical inner conductor 26. The resonant cavity 16 is designed or dimensioned to be connected or coupled to an electron tube 28, such as an ultra high frequency power amplifier tube like the RCA type 6448. Such a tube 28 isindicated in phantom in Fig. l. The outer conductor 24 of the resonant cavity lti'is electrically and directly connected to the cathode electrode 30 of the tube 28 through a metallic flange 31 and a metallic ring 33 The inner conductor 26 of the resonant cavity 16-is directly. and electrically connected to the anode electrode 32 of the tubeZS. Thus radio frequency energy produced? by the tube 28- is applied to the resonant cavity: 16; The grid electrode 35 of the: tube 28 is shown, but: the connections between the grid electrode 35 and the: resonant cavityl' are'notshown since they do not relate to the invention; Suitable connections for a cooling fluid may be placed'in the hollow inner conductor 261 of the resonantcavity l6 and connected to the appropriate elements'of'the tube'28.

The transmission line 10 and the resonant cavity 16- ice . are physically positionedso that their longitudinal axes small as possibletso as to. introduce as little discontinuity as possible into the resonant cavity 16 and the coaxial. transmission line 1%, and still provide clearance fortheconnecting element 22. In practice, it has been found that this discontinuity is, for all practical purposes, neglrg'ible. This is an important and desirable feature of the invention.

A coupling ring 3S is positioned. within the resonant cavity'ld; The coupling ring 33 comprises a cylindrical ring of metal that has a plurality ofcontacts or spring fingers 40: which are arranged anddimensioned tofrictionally' engage and contact substantially 360 of theouter surface of 'tlie inner conductor 26 of theresonant; cavity'16; This'couplingiring 38is mechanically anzll electrically connected tothe connecting element 22, which}, in'turn, is; connectedito: the movablei'portion 2000f thei inner, conductor 14 of'th'e transmission line 10. The:

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point at which the coupling ring 38, and hence the connecting element 22 contact the inner conductor 26 of the resonant cavity 16 determines the loading presented to the resonant cavity 16 by the transmission line 10. The coupling ring 38 only contacts the inner conductor 26 of the resonant cavity 16, and does not engage or contact the outer conductor 24 of the resonant cavity 16. The coupling ring 38 is moved longitudinally along or within the resonant cavity 16 by three metallic rods 42 which are connected to the coupling ring 38. The rods 42 are thus electrically connected to the inner conductor 26 of the resonant cavity 16. Consequently, it it unnecessary to insulate these rods 42 from the inner conductor 26, or to make them of an electrically insulating material. The rods 42 are spaced 120 apart, and extend longitudinally to a point. at which they are connected to a suitable gearing arrangement 44 and a motor 46 for moving the rods 42. While three rods 42 are shown, more or less may be used. Furthermore, other arrangements, such as manual devices, can be used equally Well to move the rods 42. As the rods 42 connected to the coupling ring 38 are moved longitudinally, the coupling ring 38tis also moved longitudinally, thus changing the loading presented to the resonant cavity 16. Likewise, the connecting element 22 and the movable portion 20 of the transmission line inner conductor 14 are also moved longitudinally. Thus, a practical and convenient means is provided for varying the loading on a coaxial resonant cavity.

A tuning ring 50 is also positioned in the resonant cavity 16. The tuning ring 50 comprises a cylindrical ring of metal that is designed and dimensioned to fit between the inner conductor 26 and the outer conductor 24 of the resonant cavity 16. The tuning ring 50 is provided with two sets of contacts or spring fingers 52 which frictionally engage or contact substantially 360 of the outer surface of the inner conductor 26 of the resonant cavity 16, and also frictionally engage or contact substantially 360 of the inner surface of the outer conductor 24 of the resonant cavity 16. The tuning ring 50 provides means for physically changing the physical size, and hence theresonant frequency, of the resonant cavity 16. The tuning ring 50 is moved by two rods 56 which are connected to the tuning ring 50. The rods 56 are spaced 180 apart, and extend longitudinally to a point at which they are connected to some suitable driving means, such as the gearing arrangement 58 and the motor 60. While two rods 56 are shown more or less may be used. Furthermore, other arrangements, such as a manual device, can be used equally well to move the rods 56. As the rods 56 are moved longitudinally, the tuning ring 50 is also moved longitudinally, thus changing the size and resonant frequency of the resonant cavity 16.

The end of the coaxial transmission line nearest the electron device 28 is closed by a metallic plate 64 so as to provide an integral structure. Also, an insulator 66, such as a small disc of teflon, is fastened to the tuning ring 50 so as to prevent the connecting element 22 from being directly and electrically short-circuited to the tuning ring 50. This is desired so that if the tuning ring 50 and the coupling ring 38 are independently movable, it will not be possible to short-circuit the coupling ring 38 to the tuning ring 50. Any other suitable means of preventing this short circuit can also be used, thereby eleminating the teflon disc. I

While not necessary, it is also possible to combine the driving arrangements, namely the gearing arrangements 44, 58 and the motors 46, 60, to provide a differential type of driving arrangement that permits both the coupling ring 38 and the tuning ring 50 to be moved simultaneously when the resonant frequency of theresonant cavity 16 is changed, and that permits the coupling ring 38 and the tuning ring 50 to be moved independently.- Thus, it is possible to maintain the loading presented to the coaxial resonant cavity relatively constant despite changes 4 in operating frequency; This feature permits easy and rapid adjustment of the device. 7

While the coupling device has been described in detail in connection with a coaxial resonant cavity, it can be used equally well with a coaxial transmission line. Furthermore, the coupling device can also be used with a cavity, such as a hollow, cylindrical cavity, or with a waveguide. However, in the case of a hollow cavity or waveguide, it would not be necessary to use a coupling ring, as there would be no inner conductor to engage. The coupling device would serve as a probe in such an application.

The coupling device in accordance with the invention provides a novel means for coupling energy to a transmission line or similar structure under a wide variety of operating conditions and over a wide range of frequency tuning.

What is claimed is:

1. A coupling device for a hollow transmimion line having at least an outer conductor, comprising a transmission line section having an outer conductor and an inner conductor positioned within said outer conductor of said transmission line section, said inner conductor of said transmission line section being arranged for movement along it longitudinal axis with respect to said outer conductor of said transmission line section, said outer conductor of said hollow transmission line and said outer conductor of said transmission line section being positioned so that said outer conductors contact each other along a joint wall portion for at least a portion of their respective lengths, said outer conductors each having a longitudinal slot therein at said joint wall portion, said slots registering with each other, and a rigid conductive connecting element fixedly fastened to one end of said inner conductor of said transmission line section and positioned so that it passes through said slots and into said hollow transmission line without touching said joint wall portion and said outer conductors over at least a portion of said movement.

2. A coupling device for a coaxial element having an outer conductor and an inner conductor symmetrically positioned within said outer conductor, comprising a transmission line having an outer conductor and an inner conductor symmetrically positioned within said outer conductor of said transmission line along the longitudinal axis of said transmission line, said inner conductor of said transmission line being arranged for movement along said longitudinal axis with respect to said outer conductor of said transmission line, said outer conductor of said coaxial element and said outer conductor of said transmission line being positioned so that said outer conductors contact each other along a joint wall portion for at least a portion of their respective lengths, said outer conductors each having a longitudinal slot therein at said joint wall portion to provide an opening between said coaxial element and said transmission line, a rigid conductive connecting element fixedly fastened to one end of said movable inner conductor of said transmission line and positioned so that it passes through said opening and into said coaxial element without touching said joint wall portion and said outer conductors, and a metallic coupling element connected to said connecting element within said coaxial element and positioned so that it is movable and contacts said inner conductor of said coaxial element over at least a portion of said movement of said inner conductor of said transmission line.

3. A coupling device for a coaxial element having a cylindrically shaped outer conductor and a cylindrically shaped inner conductor concentrically positioned within said outer conductor, comprising a transmission line having ametallic, cylindrically shaped outer conductor and a metallic, cylindrically shaped inner conductor concentrically positioned within said outer conductor of said transmission line, said transmission line inner conductor comprising a fixed portion and a telescoping movable P i arran e for, marathon its longitudinal axis with resp'ec saidfixecl portion Of, said inner conductor, said outer conductor of said coaxial element and 'said 'outer conductor of said transmission line being positioned so-that-their longitudinal axesare parallel and friission line, a rigid conductive connecting element fixdl'y fastened to the free end of said movable portion of said inner conductor of said transmission line and positioned so that it passes through said opening and into said coaxial element without touching said joint wall portion and said outer conductors, a metallic coupling ring connected to said connecting element and positioned around-said inner conductor of said coaxial element, said coupling ring being movable and arranged so that it contacts said inner conductor of said coaxial element over at least a portion of its movement, and means connected to said coupling ring for moving said ring in a direction parallel to said longitudinal axis of said coaxial element.

a hollow, metallic, cylindrical inner conductor concentrically positioned within said-outer conductor of said transmission line, said inner conductor of said transmisslon line having a fixed portion and a telescoping movable portion arranged for movement along its longitudinal axis with respect to said fixed, portion, said outer conductor of said cavity and said outer conductor of said transmission line being positioned so that the longitudinal axes of their outer conductors are parallel and so that said outer conductors contact each other along a joint wall portion for at least a portion of their respective lengths, said outer conductors each having a longitudinal slot therein at said joint wall portion to provide an opening between said cavity and said transmission line, a metallic coupling ring positioned around said inner conductor of said cavity and arranged to be movable and to engage the outer surface of said inner conductor of said cavity, said coupling ring being dimensioned so that it is spaced from said outer conductor of said cavity, and a metallic connecting element fixedly fastened to the free end of said movable portion of said inner conductor of said transmission line and to said coupling ring, said connecting element being positioned so-that it passes through said opening without touching said joint wall and said outer conductors.

5. A coupling device for a coaxial resonant cavity having ahollow cylindrical outer conductor and a cylindrical inner conductor concentrically positioned within said conductor, comprising a transmission line having a hollow, metallic, cylindrical outer conductor and a metallic, cylindrical inner conductor concentrically positioned within said outer conductor of said transmission line,

said inner conductor of said transmission line having a fixed portion and a' telescoping movable portion arranged ductors are parallel and so that said outer conductors outer surface. ofsaid; innerconductor of said cavity} said coupling ring beinggidimen'sioned so that it isspaced from-said outer. conductor of said cavity, a metallic connecting element fixedly fastened? to the free end of said movable portion of said inner conductor of said transmission line, and to said coupling ring, said connecting elementxbeingpositioned so that it passes through said opening: without touching said joint wall and said outer conductors, andmeansz connected to said coupling ring for moving said coupling ring in a direction parallel to said longitudinal axis of said cavity.

6. In combination, a coaxial resonant cavity having a hollow, metallic, cylindrical outer conductor and a metallic, cylindrical inner conductor concentrically positioned within said outer conductor, and a coupling device for said cavity, said coupling device comprising a transmission line having a hollow, metallic, cylindrical outer conductor and a metallic, cylindrical inner conductor concentrically positioned within said outer conductor of said transmission line, said inner conductor of said transmission line having a fixed portion and a telescoping movable portion arranged for movement along its longitudinal axis with respect to said fixed portion, said outer conductor of said cavity and said outer conductor of said transmission line being positioned so that the longitudinal axes of their outer conductors are parallel and so that the outer surfaces of said outer conductors contact each other along a joint Wall portion for at least a portion of their respective lengths, said outer conductors each having a longitudinal slot therein at said joint wall portion to provide an opening between said cavity and said transmission line, a movable metallic coupling ring positioned around said inner conductor of said cavity and having a plurality of spring fingers adapted to engage the outer surface of said inner conductor of said cavity, said coupling ring being dimensioned so that it is spaced from said outer conductor of said cavity, a metallic connecting element fixedly fastened to the free end of said movable portion of said inner conductor of said transmission line and to said coupling ring, said connecting element being positioned so that it passes through said opening without touching said joint wall and said outer conductors, and means connected to said coupling ring for moving said coupling ring in a direction parallel to said longitudinal axis of said cavity.

7. In combination, a coaxial resonant cavity having a hollow, metallic, cylindrical outer conductor and a metallic, cylindrical inner conductor concentrically positioned within said outer conductor, and a coupling device for said cavity, said coupling device comprising a transmission line having a hollow, metallic, cylindrical outer conductor and a metallic, cylindrical inner conductor concentrically positioned within said outer conductor of said transmission line, said inner conductor of said transmission line having a fixed portion and'a telescopig movable portion arranged for movement along its longitudinal axis with respect to said fixed portion, said outer conductor of said cavity and said outer conductor of said transmission line being positioned so that the longitudinal axes of their outer conductors are parallel and so that the outer surfaces of said outer conductors contact each other along a joint wall portion for at least a portion of their respective lengths, said outer conductors each having a longitudinal slot therein at said joint wall portion to provide an opening between said cavity and said transmission line, a movable metallic coupling ring positioned around said inner conductor of said cavity and having a plurality of spring fingers adapted to engage 7 opening without touching said joint' wall and said outer conductors, a metallic tuning ring positionedrbetween said inner conductoi and said outer conductor of said cavity and having a plurality of spring fingers'adapted [References Cited in the file of tins-patent UNITED STATES; PATENTS f McCouch 2 June 16, 1953 

